Multi-substrate modules are commonly used for high-resolution printheads or wide page array printheads and typically include plural substrates with adjacent overlapping and non-overlapping regions defining the area between adjacent substrates. One factor in assuring high print quality of inkjet printers with multi-substrate print modules is the control over the uniformity of ink drops ejected onto the print media.
In current systems, uniform printing is used from all columns of the multi-substrate module. However, this results in a large difference in the time delay for drops printed in the adjacent overlapping region versus the non-overlapping regions. As such, in the adjacent overlapping regions, ink is laid on ink rather than ink onto the print media, due to the adjacent overlapping substrates.
Consequently, ink laid on ink, in relation to drying time and image quality, can cause printed image quality problems due to the difference in the interaction between the ink and the media in the adjacent overlapping regions versus the non-overlapping regions. One of the image quality problems is print banding. Print banding is the appearance of repetitive horizontal bands within a printed image, which may appear as light or dark bands. Print banding is particularly undesirable in printers that require high quality printouts, such as images or photographs, where the effects of banding are more likely to be visible.
The present invention includes as one embodiment an inkjet printing method for decreasing print banding in a thermal inkjet printhead having a plurality of substrates with adjacent overlapping and non-overlapping regions between the substrates, the method comprising synchronizing a difference in time delay between ink ejected from the adjacent overlapping and non-overlapping regions of each substrate to reduce the difference.